What is "Ma'ase Shushan"?
Rashi (22): A half-Amah at the top of each [pillar], the wall was as thin as a rose (petal). The rest of the pillar, the wall was four fingers thick, and it was hollow inside. This is why the top half-Amah of each pillar was not included in their total height in Divrei ha'Yamim II, 3:15.
Radak citing Targum Yonasan, Gra (22): It is the form of roses.
Metzudas Tziyon: It is [the form of] a plant. It is called Shushan because it always has Shesh (six) leaves.
What is the meaning of "b'Ulam"?
Radak: [The form of roses was] even with (at the height of) the Ulam, i.e. the caps on the crowns.
Metzudas Tziyon: It refers to the ceiling, like Chazal said. 1
Malbim: The form of Shushan was on the wall of the Ulam at the height of the top of the pillars, i.e. 18 Amos.
I did not find this in Chazal. Some editions cite Eruvin 102. It does not mention Ulam at all. Rashi there mentions Ulam, but does not say that it refers to the ceiling! (PF)
